DE2021526A1 - Process for the preparation of alkylphenol mixtures - Google Patents

Description

Wesseling, March 31, 1970. VP / Dr.Sch.-B. / Kl.

Our reference: UK 236

Process for the preparation of mixtures of alkylphenols

The invention relates to a process for the preparation of alkylphenol mixtures with a high content of 315-dialkylphenols.

-It is known to use alkylating agents such as olefins, alcohol, phenol. To alkylate ethers or alkyl halides in the presence of catalytically active aqueous solutions of zinc halide and hydrogen halide at elevated temperatures. A molar ratio of phenol to alkylating agent such as about 1: 0.6 is preferably used. The catalyst solutions used contain about up to 20 moles of water and up to 2 moles of hydrogen halide per mole of zinc halide. The amount of catalyst solution used does not generally need to be more than about 10 % based on the phenol used. Depending on the setting of the reaction conditions, the substitution in the ortho or para position can be influenced within certain limits, but the amount of meta isomers is always relatively low. Accordingly, the dialkylphenols obtained in the alkylation consist predominantly of 2,6- and 2,4-dialkylphenols, while the proportion of 3,5-dialkylphenols remains low. · ■

It has now been found that an alkylphenol mixture with a high content of 3i5-dialkylphenols can be obtained by reacting phenol with lower olefins, alcohols, ethers or alkyl halides at elevated temperatures and optionally at elevated pressures in the presence of an aqueous solution of zinc chloride or zinc bromide and a corresponding hydrogen halide can be obtained if in the presence of more than 10 % catalyst solution, based on the phenol used, initially at temperatures up to about 120 with a molar ratio of alkylating agent to phenol of more than 0.8: 1 aJkylie.rt, then the Bringing the alkylation mixture to a temperature of about 160-18O, lower-boiling constituents being removed from the mixture by distillation to the extent that

109 849/193 1

BATH ORIGINAL

Our reference: UK 236

the water content of the catalyst solution is not more than about 30 moles per mole of zinc halide, and the equipment is kept at a temperature of at least 10 until the reaction is complete. The molar ratio of alkylating agent to phenol is expediently adjusted to about 1: 1. If this ratio is increased too much, ortho- or para-substitution may be preferred. The catalyst solution used can initially contain a water content greater than 3.0 moles per mole of zinc halide. The required higher concentration is set by removing water during heating to over 16O. If too much hydrogen halide escapes, this must be replenished so that the catalyst solution has a content of at least 0.05 mol of hydrogen halide per mol of zinc halide. The amount of catalyst solution, based on the phenol used, can be, for example, 15 % and more. The reaction can also be carried out under increased pressure. The reaction time depends on the conditions chosen, in particular also on the catalyst concentration. It is generally up to about 6 hours, but can of course also be chosen to be longer. After the reaction has ended, the solution can be removed from the mixture, for example by washing it out with water, if appropriate at an elevated temperature. This can be carried out in a known manner, in one or more stages. It may be advantageous to add an inert diluent, for example heptane, cyclohexane, to the mixture before washing it out in order to facilitate the separation of the organic and aqueous layer. The alkylation mixture is worked up in a known manner, for example by distillation. Unconverted phenol, diluent and catalyst solution, these after appropriate concentration, can be reused or circulated in the usual way. It has been shown that the resulting 2, *) - · and 2,6-dialkylphenols can be reacted in whole or in part, since a further proportion of 3 _S 5-dialkylphenol is formed from these compounds. The process can be carried out batchwise or continuously. The 3? 5-dialkylphenols obtained are, for example. valuable components for the production of synthetic resins.

BATH ORIGINAL

109849/1931

Our reference: ITK 236

B e i ρ ρ -i e. 1 :

1 mol of phenol was reacted with 1 mol of propylene in the presence of 30 % _Λ based on phenol, a catalyst solution which contained 3.5 mol of water per mol of zinc bromide and 0.2 mol of HBr, initially at about 110%. After about 1 hour, the temperature was slowly increased to 175, lower-boiling fractions, mainly water and some phenol and propyl bromide, being removed by distillation until the catalyst solution contained less than 2.0 moles of water per mole of zinc bromide. The temperature was held at the stated level for a further h hours. The reaction mixture was then cooled to about 60, mixed with the same volume of a mixture of 90% cyclohexane and 10 % benzene, washed with water until the catalyst was completely removed from the organic layer at about 60 and then the alkylate was worked up by distillation. The yield, based on the alkylating agent, was 100 %, based on phenol approx. 80 %. After separating off the diluent and the unreacted phenol, the alkylphenol mixture contained 62.3 % monoisopropylphenols,

32.7 % diisopropylphenols,

5iO # higher alkylated compounds. The proportion of 3,5-diisopropylphenol was 19i9 %

If the experiment is 'repeated' with a molar ratio of Propylene to phenol like 0.7 * 1 »but otherwise under the same conditions, the alkylphenol mixture consisted of

78.5 % monoisopropylphenol, 19 | 2 % diisopropylphenol, 2.3 % higher alkylated compounds.

The proportion of 3,5-diisopropylphenol was 10.k%,

BATH ORIGINAL

109849/1 9-3 1

Claims (3)

Our reference: UK 236 Patent claims: My process for the preparation of alkylphenol mixtures with a high content of 3,5-dialkylphenols by reacting phenol with lower olefins, alcohols, ethers or alkyl halides at elevated temperatures and optionally elevated pressures in the presence of a. aqueous solution of zinc chloride or zinc bromide and a corresponding hydrogen halide, characterized in that in the presence of more than 10 % catalyst solution, based on the phenol used, initially at temperatures up to about 120 with a molar ratio of alkylating agent to phenol of more than 0.8 : 1 alkylated, then the alkylation mixture is brought to a temperature of about 160-180 °, lower-boiling constituents being removed from the mixture by distillation to such an extent that the water content of the catalyst solution is no more than about 3 »0 moles per mole of zinc halide , and maintaining the mixture at a temperature of at least 150 until the reaction is complete. 2. The method according to claim 1), characterized in that the Hydrogen halide content of the catalyst solution during the entire reaction to at least 0.05 mol per mol of zinc chalcide adjusts. . ' 3. The method according to claim 1) and 2), characterized in that one the 2, * f- and 2,5-dialkylphenols obtained from the alkylation mixture returns to implementation. 109849/1931